JP 4209775 B2 describes an example of a female terminal having a radially resilient contact member. As shown in FIGS. 12 and 13, this female terminal 10 has a cylindrical sleeve 20, and a cylindrical contact member 30 inserted inside the cylindrical sleeve 20. A plurality of engaging parts 21 are arranged at an interval in a circumferential direction, at both axial ends of the cylindrical sleeve 20. The cylindrical contact member 30 has a plurality of axially extending contact strips (thin strips for contacts) 31, and also has a plurality of engaging parts 32 arranged at an interval in a circumferential direction, at both axial ends of the cylindrical contact member 30.
The engaging parts 32 at the both ends of the cylindrical contact member 30 are engaged with the engaging parts 21 at the both ends of the cylindrical sleeve 20 in a twisted positional relationship, whereby an assembly of the plurality of the contact strips 31 held in a twisted state forms a hyperboloid. The female terminal 10 is configured such that a portion of the hyperboloid formed by the cylindrical contact member 30 that has been bent in an inwardly convex manner serves as a spring portion having radial resiliency. When a male terminal, which is not shown, is inserted into this female terminal 10, the contact member 30 pushed by the male terminal is elastically deformed and applies a contact load to the male terminal, whereby an electrical connection between the male terminal and the female terminal is made.
According to the female terminal described above, the contact member is formed in a hyperboloidal shape in advance in a permanent manner from the beginning, before the male terminal is inserted. Thus, the male terminal needs to be inserted into the female terminal, while receiving a spring load from the contact member. Therefore, there is a problem that the spring load causes a friction resistance and increases the insertion load. Because the insertion involves receiving of the friction resistance, there is also a problem that contact portions of the male terminal and the female terminal are easily worn away.